SIP (Session Initiation Protocol) servers have been distributed interconnecting the IP (Internet Protocol) phones serving as clients. Further, a method for connecting storage devices to a network using a protocol called an Internet Small Computer Systems Interface (iSCSI) is being distributed. For example, a method has been proposed improving the connectibility between a terminal connected to another local address system and an iSCSI storage device by using a protocol conversion apparatus which converts between the SIP and the iSCSI protocol See, for example, Japanese Patent Application Laid-Open No. 2011-257793.
When a server connected to a security ensured network storage through a switch fails, a method for connecting another server to the storage has been suggested by switching the switch to take over an existing security settings. See, for example, Japanese Patent Application Laid-Open No. 2007-164394.